The goals of this project are to characterize the natural history of mucocutaneous herpes simplex virus infections in normal and immune-impaired patients. In particular, we focus on genital herpes and the impact of brief and chronic acyclovir treatments on the natural history and expression of disease, and the in vitro sensitivity of virus recovered from patients. We have attempted to characterize the incidence of asymptomatic virus shedding from the genital area and to ascertain whether acyclovir alters those rates. The first convenient and efficient model of reactivation of herpes simplex virus infections in humans involving ultraviolet light exposure to previously infected skin sites has been established, and should serve to expand our comprehension of the temporal events and factors involved in disease expression.